Transcript Issues in Microeconomics Econ 101

Chapter 3
Income and
Interest Rates:
The Keynesian
Cross Model
and the IS Curve
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Business Cycles and the Theory
of Income Determination
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•
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Remember that minimizing fluctuations in real GDP is
important. Revise the volatilia and stabilia cases.
Business cycles in USA
Figure 3.1
Note that the goals of monetary policy and fiscal policy is to
dampen business cycle fluctuations and promote a steady
economic growth of real GDP.
This is, as shown in the above figure, is far from reality.
Ups and downs in real GDP are basically caused by changes in
shocks to aggregate demand (a significant change in desired
spending by consumers, business, government and foreigners).
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The Volatile Business Cycle
• The “Great Moderation” refers to the 1986-2007 period where
business cycle fluctuations noticeably diminished.
• The Global Economic Crisis or “Great Recession” followed
the “Great Moderation.”
– Casts doubt on belief of the improved effectiveness of
monetary and fiscal policy in the 1986-2007 period
– Alternate explanation: Shocks were moderate 1986-2007
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Figure 3-1 Real GDP Growth
in the United States, 1950–2010
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• Improved performance of anti-cyclical fluctuations
can be due to:
- demand shocks are smaller and less important
- monetary and fiscal policies become more effective
- a change in the conditions that make fiscal and monetary
policies more effective.
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The Volatile Business Cycle
• Aggregate Demand (AD) is the total amount of desired
spending expressed in current (or nominal) dollars.
– A demand shock is a significant change in desired spending by
consumers, business firms, the government or foreigners.
• Algebraically, any change in C, I, G or NX
•
Aggregate Supply (AS) is the amount that firms are
willing to produce at any given price level.
– A supply shock is a significant change in costs of production for business
firms, including wages and the prices of raw materials, like oil.
• AS and supply shocks will be considered in Chapters 8 and 9.
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Income determination and the price
level
•
Simplifying assumption:
– The price level (P) is fixed in the short run.
• Implication: All changes in AD automatically cause changes in real
GDP by the same amount and in the same direction.
Change in y = change in AD/p(fixed price)
• Is there any evidence to support the assumption that prices are fixed in the short
run?
1. Price labels are printed and expensive to reprint
2. Prices of mail order catalogues are set for the entire season
3. Wages and salaries usually change every year and perhaps in more than
that.
• Therefore, changes in AD are directly translated into changes in real GDP.
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• What we explain and what we take as given?
• The variables that an economic theory tries to explain are called
endogenous variables.
– Examples: Output and interest rates
•
Exogenous variable are those that are relevant but whose
behavior the theory does not attempt to explain; their values are
taken as given.
– Examples: Money supply, government spending, tax rates
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Consumption and Savings
•
The consumption function is any relationship that describes the
determinants of consumption spending.
• General linear form: C = Cα + c(Y – T) where…
• Cα = Autonomous consumption
• c = marginal propensity to consume
• c(Y – T) = induced consumption
C = 500 + .75 (Y-T)
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Consumption and Savings
• Savings (S) = Y – T – C
Substituting in C from above yields:
S = Y – T – [Cα + c(Y – T)]
S = – Cα + (1 – c)(Y – T)]
where…
• (1 – c) = marginal propensity to save (s)
S=-500+.25(Y-T)
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Factors Affecting Cα
•
•
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Interest Rates (r): When r↓  borrowing is cheaper
for consumers  Cα↑
– Example: Low interest rates in 2001-04 stimulated consumption of automobiles and
other consumer products.
Household Wealth (W) is the total net value of all household assets (minus any debt),
including the market value of homes, possessions such as automobiles, and
financial assets such as stocks, bonds and bank accounts.
– If W↑  HH spending can ↑ even if income is fixed  Cα↑
– Example: The 1990’s stock market boom raised consumption.
The set of Financial Market Institutions determines the ease with which households
can borrow to buy “big-ticket” items.
– Example: From 2001-06, loans were easily obtained, which helped fuel the housing
bubble.
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Figure 3-2 A Simple Hypothesis
Regarding Consumption Behavior
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The economy in and out of
equilibrium
• The four components of total expenditures are
E ≡ C + I + g + NX
• Of these components of E, we assume that spending on C, G and NX is
planned.
• Only investment can either be planned Ip or unplanned Iu.
• Business firms adjust production until Iu is eliminated, i.e., if
• Iu > 0 output will be reduced
• Iu < 0 output will be will be increased
• Iu=0 there is no pressures in the economy for change in output when,
• i.e,
Y = Ep
Ep = C + Ip + G + NX
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• Planned expenditures equals
Ep = Ca + c(Y-T) + Ip + G + NX
• Note that consumption is composed of autonomous and induced.
• Autonomous planned spending
• Autonomous planned spending (Ap) is the spending that does not
depend on total income (Y); i.e.,
Ap = E – cY = Ca – cTa + Ip + G + NX
(cY induced consumption)
• -cTa is the effect of autonomous taxes in reducing C (note that we
assume that taxes as autonomous).
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• So Ap excludes induced spending only.
• Assume that Ip=1200, NX=-200, Ta=0, G=0, then Ap equals
Ap = 500 – 0.75(0) + 1200 + 0 – 200 = 1500
• Note that total planned expenditure Ep has two components:
Ep = Ap + cy
• When is the economy in equilibrium.
• Equilibrium is a situation in which there is no pressure for
change. The economy is out of equilibrium when firms are forced
to raise or lower their production.
• i.e, when production and income are equal to planned
expenditures. See figure 3-3
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• Now we have learned that Ep has two parts Ap and cY, i.e.,
Ep = Ap + cY
Ep = 1500 + .75 Y
• What happens out of equilibrium
• Planned expenditure fall short of income (distance HJ),
unintended inventory investment (Iu).
• Production and income will be cut till Iu=0.
• Not at point J
Y=E
Y = Ep + Iu
When Iu=0, then Y = Ep
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Figure 3-3 the Keynesian Cross
Model of Income Determination.
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Figure 3-3 the Keynesian Cross Model
of Income Determination.
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Table 3-1 Comparison of the
Economy’s “Always True” and
Equilibrium Situations
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• Determining of Equilibrium Real GDP
• How do we calculate the equilibrium level of real GDP? We know
that Y = Ep, or
Y = Ap + cY
(1-c) Y = Ap
sY = Ap
sY = Ap
(.25Y=1500)
• The equilibrium income is
Y = Ap/s
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The Multiplier Effect
• Any change in Ap will cause a change in equilibrium income.
• Suppose that businesses raise their investment by 500, i.e., Ap
increases from 1500 (Ap0) to 2000 (Ap1). The effect of a change
in Ap can be illustrated.
• Calculating the Multiplier
• To calculate the equilibrium level of income in the new and old
situations. Note
– New equilibrium
– Subtract from old
– Equals change in income
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Y1 = Ap1/s = 2000/.25 = 8000
Y0 = Ap0/s = 1500/.25 = 6000
∆Y = ∆Ap/s = 500/.25 = 2000
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• The multiplier k is ∆Y over ∆Ap
Multiplier k = ∆Y/∆Ap = 1/s
∆Y/∆Ap = 1/.25 = 4
• Look at the figure and note that
k = ∆Y/∆Ap = RJ/RB = 1/s (s = RB/RJ)
k = 2000/500 = 4
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Figure 3-4 The Change in Equilibrium
Income Caused by a $500 Billion Increase in
Autonomous Planned Spending
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• Examples of the Multiplier Effect in Action
• If planned expenditure rises, real income must rise by 1/s as
much.
• suppose that an airway company bought $4 billion of Boeing
aircrafts. This will raise Boeing workers income by 4 billion, out
of which they will soon spend 0.75 on goods and services, that
will raise output by 3 billion of consumer goods in the second
round. A rise in income by 3 billion will raise spending by
2.25,….., and so on.
• Total change in income = 4 x 1/.25 = 16 billion
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Shifts in Planned Spending
• Recall: EP = C + IP + G + NX = AP + cY
where AP = Cα – cTα + IP + G + NX
• Any increase in AP will shift up EP on the Keynesian Cross
Diagram.
– Effect on Y: ∆Y = (1/s) ∆AP
where
• If c changes, the EP line will rotate
• If the effect on Y is negative, fiscal policy can be used to offset
the effect.
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Government Budget Deficit and its
Financing
• Suppose an increase in G is financed by issuing bonds
– Cα , Tα , IP and NX are unchanged  ∆Y = (1/s) ∆G
– What happens to the “Magic Equation” ?
•
•
•
•
Recall: (T – G) = (I– S) + NX
In “∆” form: (∆T – ∆G ) = (∆I – ∆S) + NX
Since T, I and NX are constant  ∆G = ∆S
Using ∆Y = (1/s) ∆G  ∆G = s∆Y… but s∆Y = ∆S !!!
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Government Budget Deficit and its
Financing
– Result: The higher level of government purchases leads to an
increase in income, which yields the higher level of savings
needed for households to purchase the bonds to pay for the
increase in G!
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Government Budget Deficit and its
Financing
– The Tax Multiplier
• The tax multiplier
• As an alternative to using G by 500, the government can reduce
taxes by 667 ((2000/0.75)*0.25) to have the same impact. Thus;
∆Y = -(.75)(-667)/.25 = 500/.25 = 2000
• The multiplier is –c/s:
∆Y/∆Ta = -c/s
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The Balanced Budget Multiplier
• Suppose an increase in G is paid for by raising taxes
(i.e. the government is running a balanced budget)
–
–
–
–
∆G = ∆Tα (while IP and NX are unchanged)
∆Y = (1/s) ∆AP = (1/s)(∆G – c∆Tα) = (1/s)(∆G – c ∆G)
Recall: s = (1-c)
Then:
– Result: The balanced budget multiplier is 1!
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• The demand for autonomous planned spending
• We know that autonomous spending is composed of 5
components. There is a negative relationship between interest
rates and Ip+Ca, the other 3 do not depend on interest (GcTa+NX). See figure.
• Shifts in the Ap demand schedule
• A change in G, T and NX shift the Ap demand schedule. A shift
in business expectations, and improvement in consumer
confidence will also shift the Ap demand schedule.
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Figure 3-5 Relation of the Various Components
of Autonomous Planned Spending to the Interest
Rate
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• The IS curve
• Ap depends on interest rate. Real GDP and real income depend
on Ap, therefore, real GDP and real income depend on interest
rate. The IS curve shows the different combinations of interest
rate and real income that are compatible with equilibrium.
• How to derive the IS curve.
• the LHS OF figure 3-9 shows the demand for Ap at different
levels of interest rates. Assume that there are no G, T, and NX,
so that Ap consists of Ip + Ca, both is negatively related to
interest rate. Given a multiplier of 4, at different points of Ap,
real income is determined.
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Figure 3-6 Relation of the IS Curve to
the Demand for Autonomous Spending
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• What the IS curve shows
• The IS shows different combinations of interest rate (r) and
income (y), at which the market is in equilibrium when y = Ep.
At any point out of the IS the economy is out of equilibrium.
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Investment Volatility and Business
Cycles
Investment Falls Relative
to GDP in Every Recession
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